Cummins 12V pistons: Marine versus Mahle

AsTroSS

AsTroSS

problems start @80 psi
Joined
May 10, 2006
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Here is side by side pictures of Cummins original (at right) 370HP piston and aftermarket Mahle Marine piston.

Mahle piston bolw diameter is little bit smaller and not so deep as Cummins original.

Like you see, also piston ring landing is different.

Cummins piston looks heavier ,but I do not knew weight difference. I will try to weight it next week.
 

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Looks like the original 370 has the teflon coating on the skirt and the Mahle does not.

Also, both ring lands on the 370 have the alloy insert (I forget which alloy is used?), and the Mahle only uses it on the top ring land...
 
sorry for hijack, but does anyone know how much it would be to just mill the stock pistons? or would I be waisting my time?
 
How much what? $$$ or compression drop? Lots of shops do it for Valve clearance.
 
yeah I was wanting to lower my comp. so I could run higher time and the extra valve clearance is good also. I was looking for a price est. and how much to take off? does 15:1 sound good?
 
Haisleys will mill stock pistons. Issue with milling them is you further increase the chance of getting the fuel out of the bowl. I know many a guys that run 30+ with just .020 headgasket.
 
But wait, the 370 is better than any other piston, cause Don said so right :bs:

Jim
 
Good stuff to know! Does anyone know how much more timing the Cummins Marines will take over a stock piston? How much does a full set generally run?
 
That is all based on a stock block and head, start decking them and see were it goes, the piston I posted is 17.5 but 16.7 on my motor with .012 off the block and .005 off the head.

Jim
 
Jim Fulmer said:
That is all based on a stock block and head, start decking them and see were it goes, the piston I posted is 17.5 but 16.7 on my motor with .012 off the block and .005 off the head.

Jim
Click to expand...

I thought cutting the head had no effect on compression. Being a flat fire deck, and not a bowl like a gasser head.
 
Boy, thats neat to hear that the 370hp engine is 24* stock. Never really thought of timing diff. in the higher hp engines, whats the highest known hp for a 5.9 right out of the box from cummins? Also i went with cummins .20 gasket myself and the block nor the head has ever been machined shouldnt this lower my static from 17.5 to in the 15's?? I miced the new gasket at .100" vers the compressed stocker i removed was .60", so my math came up with .40" thicker not .20" surly that sucker wont compress .20" would it? Thanks guys
 
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